Angular-Docs-Cn/aio/content/examples/accessibility/src/app/progress-bar.component.css

    :host { 
      display: block; 
      width: 300px; 
      height: 25px; 
      border: 1px solid black; 
      margin-top: 16px;
    }
    
    .bar { 
      background: blue; 
      height: 100%; 
    }